Summary: This is a solid stove that dependably does most simple cooking in the backcountry.
This was one of my first pieces of backpacking gear. I've used it on muti-day trips to the Beartooths in Montana, the Winds in Wyoming, the Smokeys in North Carolina, and a bike tour in Utah/Colorado, as well as many shorter trips.
It's lasted me a long time and whenever its had problems, a quick cleaning has always solved the issue. I'm completely satisfied with how its handled rigorous use. I just wish the pump were metal.
It uses fuel at about the same rate as most liquid fuel stoves. I haven't done any testing like I have with the Dragonfly, but my impressions based on the trips I've taken each on is that the Whisperlite is nearly equivalent or slightly more efficient with fuel. It is lighter than the Dragonfly, but heavier than canister stoves and some other liquid fuel stoves, so it really depends on the use you want from it.
It's a very reliable stove and it's easy to clean. For these reasons, it shouldn't detract from any trip. The main issue I have with the Standard model, which I own, is that it only burns white gas, but that's easily solved for $10 if you just get the International instead. Another minor complaint I have is that it doesn't simmer very well (it does a little, just not well) and it can't bake at all. This significantly limits its usability. These two reasons are why I almost always carry my Dragonfly instead.
The Whisperliite is the standard liquid fuel stove for good reason: it's durable, dependable, and not that expensive. It's one of the least expensive liquid fuel stoves and does about all you need a stove to do. I don't think there's another stove out there that can match the Whisperlite's value. The Whisperlite is a simple workhorse. It gets the job done and doesn't have any frills.The International version may be the best introductory stove.